package com.tte.common.utils;

import lombok.extern.slf4j.Slf4j;
import org.apache.commons.codec.binary.Base64;
import org.springframework.stereotype.Component;

import javax.crypto.Cipher;
import java.security.*;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
/**
 * 非对称加密算法需要两个密钥来进行加密和解密，
 * 分别是公钥和私钥。需要注意的一点，这个公钥和私钥必须是一对的，如果用公钥对数据进行加密，那么只有使用对应的私钥才能解密，反之亦然。
 * 由于加密和解密使用的是两个不同的密钥，因此，这种算法叫做非对称加密算法。
 * @Author: DongWH
 * @Date: 2022/11/7 17:36
 */


/**
 * RSA加解密工具类，实现公钥加密私钥解密和私钥解密公钥解密
 */
@Slf4j
@Component
public class RSAUtils {
    private static final String src = "abcdefghijklmnopqrstuvwxyz";

    public static void main(String[] args) throws Exception {
        log.debug("\n");
        RSAKeyPair keyPair = generateKeyPair();
        log.debug("公钥：" + keyPair.getPublicKey());
        log.debug("私钥：" + keyPair.getPrivateKey());
        log.debug("\n");
        test1(keyPair, src);
        log.debug("\n");
        test2(keyPair, src);
        log.debug("\n");
    }

    /**
     * 公钥加密私钥解密
     */
    private static void test1(RSAKeyPair keyPair, String source) throws Exception {
        log.debug("***************** 公钥加密私钥解密开始 *****************");
        String text1 = encryptByPublicKey(keyPair.getPublicKey(), source);
        String text2 = decryptByPrivateKey(keyPair.getPrivateKey(), text1);
        log.debug("加密前：" + source);
        log.debug("加密后：" + text1);
        log.debug("解密后：" + text2);
        if (source.equals(text2)) {
            log.debug("解密字符串和原始字符串一致，解密成功");
        } else {
            log.debug("解密字符串和原始字符串不一致，解密失败");
        }
        log.debug("***************** 公钥加密私钥解密结束 *****************");
    }

    /**
     * 私钥加密公钥解密
     *
     * @throws Exception
     */
    private static void test2(RSAKeyPair keyPair, String source) throws Exception {
        log.debug("***************** 私钥加密公钥解密开始 *****************");
        String text1 = encryptByPrivateKey(keyPair.getPrivateKey(), source);
        String text2 = decryptByPublicKey(keyPair.getPublicKey(), text1);
        log.debug("加密前：" + source);
        log.debug("加密后：" + text1);
        log.debug("解密后：" + text2);
        if (source.equals(text2)) {
            log.debug("解密字符串和原始字符串一致，解密成功");
        } else {
            log.debug("解密字符串和原始字符串不一致，解密失败");
        }
        log.debug("***************** 私钥加密公钥解密结束 *****************");
    }

    /**
     * 公钥解密
     *
     * @param publicKeyText
     * @param text
     * @return
     * @throws Exception
     */
    public static String decryptByPublicKey(String publicKeyText, String text) throws Exception {
        X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(Base64.decodeBase64(publicKeyText));
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        PublicKey publicKey = keyFactory.generatePublic(x509EncodedKeySpec);
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.DECRYPT_MODE, publicKey);
        byte[] result = cipher.doFinal(Base64.decodeBase64(text));
        return new String(result);
    }

    /**
     * 私钥加密
     *
     * @param privateKeyText
     * @param text
     * @return
     * @throws Exception
     */
    public static String encryptByPrivateKey(String privateKeyText, String text) throws Exception {
        PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(Base64.decodeBase64(privateKeyText));
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        PrivateKey privateKey = keyFactory.generatePrivate(pkcs8EncodedKeySpec);
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.ENCRYPT_MODE, privateKey);
        byte[] result = cipher.doFinal(text.getBytes());
        return Base64.encodeBase64String(result);
    }

    /**
     * 私钥解密
     *
     * @param privateKeyText
     * @param text
     * @return
     * @throws Exception
     */
    public static String decryptByPrivateKey(String privateKeyText, String text) throws Exception {
        PKCS8EncodedKeySpec pkcs8EncodedKeySpec5 = new PKCS8EncodedKeySpec(Base64.decodeBase64(privateKeyText));
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        PrivateKey privateKey = keyFactory.generatePrivate(pkcs8EncodedKeySpec5);
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.DECRYPT_MODE, privateKey);
        byte[] result = cipher.doFinal(Base64.decodeBase64(text));
        return new String(result);
    }

    /**
     * 公钥加密
     *
     * @param publicKeyText
     * @param text
     * @return
     */
    public static String encryptByPublicKey(String publicKeyText, String text) throws Exception {
        X509EncodedKeySpec x509EncodedKeySpec2 = new X509EncodedKeySpec(Base64.decodeBase64(publicKeyText));
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        PublicKey publicKey = keyFactory.generatePublic(x509EncodedKeySpec2);
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.ENCRYPT_MODE, publicKey);
        byte[] result = cipher.doFinal(text.getBytes());
        return Base64.encodeBase64String(result);
    }

    /**
     * 构建RSA密钥对
     *
     * @return
     * @throws NoSuchAlgorithmException
     */
    public static RSAKeyPair generateKeyPair() throws NoSuchAlgorithmException {
        // KeyPairGenerator类用于生成公钥和私钥对，基于RSA算法生成对象
        KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");
        // 初始化密钥对生成器
        keyPairGenerator.initialize(1024);
        // 生成一个密钥对，保存在keyPair中
        KeyPair keyPair = keyPairGenerator.generateKeyPair();
        RSAPublicKey rsaPublicKey = (RSAPublicKey) keyPair.getPublic();
        RSAPrivateKey rsaPrivateKey = (RSAPrivateKey) keyPair.getPrivate();
        String publicKeyString = Base64.encodeBase64String(rsaPublicKey.getEncoded());
        String privateKeyString = Base64.encodeBase64String(rsaPrivateKey.getEncoded());
        RSAKeyPair rsaKeyPair = new RSAKeyPair(publicKeyString, privateKeyString);
        return rsaKeyPair;
    }


    /**
     * RSA密钥对对象
     */
    public static class RSAKeyPair {

        private String publicKey;
        private String privateKey;

        public RSAKeyPair(String publicKey, String privateKey) {
            this.publicKey = publicKey;
            this.privateKey = privateKey;
        }

        public String getPublicKey() {
            return publicKey;
        }

        public String getPrivateKey() {
            return privateKey;
        }

    }

}